Liquid crystal display devices have advantages such as low profile, low power consumption, and high definition, and have proliferated in the TV field along with an increase in screen size owing to the advancement of manufacturing techniques. It has been pointed out that an image displayed on a liquid crystal display device is low in contrast feeling (narrow in dynamic range) due to the display method in use. For this reason, in recent years, many efforts have been made on development of techniques associated with improvement in image quality of display images.
PTL 1 discloses a direct backlight having a plurality of light sources (cold cathode fluorescent tubes 101) partitioned from each other, for each illumination region, by partition walls 102, as shown in FIG. 9. White light emitting diodes (LEDs, not shown) for luminance adjustment are arranged below the light sources. PTL 1 describes that a lens, diffuser panel, and optical sheet (not shown) are provided on each LED to increase a luminance ratio of illumination light between the adjacent illumination regions, that is, a dynamic range. PTL 1 also describes that partitioning the respective illumination regions by using partition walls 102 can prevent mutual interference between illumination light at the adjacent illumination regions, thereby obtaining an image with higher quality.